Dehydration causes low blood pressure?

[rhan101277]

I was reading in my anatomy book about how the kidneys either decide to retain water or expel water through urine. It has some comment about how blood pressure could be affected. Is this why saline is administered? I thought administering saline dilates vessels resulting in lowered blood pressure. If you have a individual who is dehydrated it would seem to me that administering saline solution would result in further lowering of blood pressure.

Maybe I am thinking wrong?

 

[Ridryder911]

Here is a web site that might be able to clarify it up for you. It is more in detail than a simple answer that can be given.

http://www.hemodynamicsociety.org/hemodyn.html

Basically there are three things (although there are several hundred other factors) that are primarily to control blood pressure.

The:
Pump (heart)
Volume (fluid, such as blood, cellular fluid, etc)
Vessel tone ( constriction, dilatation of blood vessels- arteries, veins, arterioles, capillaries)

Attempt to learn the very basics and terms and functions of hemodynamics. Stroke volume, Total Peripheral Resistance, Cardiac Output.

Once one has mastered hemodynamics, one can understand CHF, Shock Syndromes, V/q mismatch, etc...


Now I ask, what happens when any fluid is lost? What does Saline consist of? What happens to the cells during dehydration?
Good luck!

R/r 911

 

[mikeylikesit]

hemodynamics was the toughest part of A&P...uhh, all those figures and formulas. it takes a while but once you get everything down a ton of the bodies systems make better sense.

 

[mycrofft]

Is there "pure dehydration"?

FONT="Courier New"] If dehydration is due in large part to voluntary poor water intake you can suspect poor food/protein/electrolyte intake. Some folks's physiology adapts better than others, others' fail in ways we don't often see; I've seen normotensive and hypotensive, but all the hypotensives lost consciousness.
I've never seen pure dehydration except perhaps anorexic elderly patients; it has otherwise almost always been linked to heat exhaustion, regular exhaustion, or vomiting. Teaching demands clear lines, the world doesn't.
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